1. Technical Field
The present invention relates generally to an improved data processing system, and in particular to a method and apparatus for identifying connections between data processing systems. Still more particularly, the present invention provides a method and apparatus for establishing connections with a process on a data processing system with partitioning of System Area Network (SAN) end nodes to accommodate Logical Partitioning (LPAR).
2. Description of Related Art
In a System Area Network (SAN), the hardware provides a message passing mechanism which can be used for Input/Output devices (I/O) and interprocess communications between general computing nodes (IPC). Consumers access SAN message passing hardware by posting send/receive messages to send/receive work queues on a SAN channel adapter (CA). The send/receive work queues (WQ) are assigned to a consumer as a queue pair (QP). The messages can be sent over five different transport types: Reliable Connected (RC), Reliable datagram (RD), Unreliable Connected (UC), Unreliable Datagram (UD), and Raw Datagram (RawD). Consumers retrieve the results of these messages from a completion queue (CQ) through SAN send and receive work completions (WC). The source channel adapter takes care of segmenting outbound messages and sending them to the destination. The destination channel adapter takes care of reassembling inbound messages and placing them in the memory space designated by the destination's consumer. Two channel adapter types are present, a host channel adapter (HCA) and a target channel adapter (TCA). The host channel adapter is used by general purpose computing nodes to access the SAN fabric. Consumers use SAN verbs to access host channel adapter functions. The software that interprets verbs and directly accesses the channel adapter is known as the channel interface (CI).
A Local Identification (LID) refers to a short address used to identify a Channel Adapter (CA) port within a single subnet. A source LID (SLID) and a destination LID (DLID) are the source and destination LIDs used in a SAN communication packet header. The LID Mask Control (LMC) field in the SAN communication packet identifies the number of low order bits that can be used for routing the packet through different paths in the network. This means that a single CA port has up to 2LMC LIDs assigned to it.
It is common for a system to be divided into Logical Partitions (LPARs) where various resources are allocated to a various user. For example, some systems can have various processors dedicated to one instance of the operating system and other processors in the same system allocated to another instance. The purpose of LPAR is so that if there is failure in the hardware or software, at most just the users in the same partition are affected and not the other partitions.
The problem occurs on how to route SAN packets to the correct partitions in an efficient manner, when those partitions are sharing a SAN port.